I have 2 tables. One table lists all the records of items we track. The other table contains flags of attributes of the records in the first table.
For example, Table 1 has columns
Tab1ID, Name, Address, Phone
Table 2 has these columns
Tab2ID, Tab1ID, FlagName
There is a 1 to Many relationship between Table1 and Table2 linked by Tab1ID.
I'd like to create a query that has all the records from Table1 in it. However, if one of the records in Table2 has a Flagname=Retired (with a matching Tab1ID) then I want a "Y" to show up in the select column list otherwise an "N".
I think it might look something like this:
Select Name, Address, Phone, (select something in table2)
from Table1
where Tab1ID > 1;
It's the subquery in the column that has me stumped.
Pat
You can use exists:
Select t1.*,
(case when exists (select 1
from table2 t2
where t2.tab1id = t1.tab1id and t2.flagname = 'Retired'
)
then 'Y' else 'N'
end) as retired_flag
from Table1 t1;
I would do a normal join returning multiple records, but convert them to bits with case statements. Then use that as the subquery and pull the max value for each bit column.
select
name
,address
,phone
,max(retired_flag)
from (
select
table1.name
,table1.address
,table1.phone
,case when table2.flagname = 'retired' then 1 else 0 end as [retired_flag]
from table1
left join table2
on table1.tab1id = table2.tab1id
where tab1id > 1
) tbl
group by
name
,address
,phone
Related
SO I have 2 tables and would like to SUM the total of a column in one table where 2 other columns match in another table.
In table1 I have acc_ref and bill_no.
acc_ref is different but bill_no could be 1-10 (so 2 or more acc_ref could have the same bill_no)
In table2 I have acc_ref, bill_no and tran_amnt.
Εach acc_ref has multiple rows and I want to SUM the tran_amnt but only if acc_ref and bill_no both match in table1.
I tried this but I get an error
'The columns in the SELECT clause must be contained in the GROUP BY
clause'
select a.acc_ref, a.bill_no
from table1 a
where exists (select acc_ref, bill_no, SUM (tran_amount)
from table2 b
where a.acc_ref = b.acc_ref
and a.bill_no = b.bill_no
group by acc_ref)
Apologies if this is very basic and obvious but I'm struggling!!
In you description it seems like table1 does not contain any useful information. Because both columns you give also exist in table2. So if nothing else from table1 is needed, you could just remove table1 from the query). Still with your problem you should do a simple join
SELECT a.acc_ref, a.bill_no, SUM(b.tran_amount)
FROM table1 a
JOIN table2 b ON b.acc_ref = a.acc_ref AND b.bill_no=a.bill_no
GROUP BY a.acc_ref, a.bill_no
I believe you should use case:
Sample:
SELECT
TABEL1.Id,
CASE WHEN EXISTS (SELECT Id FROM TABLE2 WHERE TABLE2.ID = TABLE1.ID)
THEN 'TRUE'
ELSE 'FALSE'
END AS NewFiled
FROM TABLE1
I have two tables in Access, one containing IDs (not unique) and some Name and one containing IDs (not unique) and Location. I would like to return a third table that contains only the IDs of the elements that appear more than 1 time in either Names or Location.
Table 1
ID Name
1 Max
1 Bob
2 Jack
Table 2
ID Location
1 A
2 B
Basically in this setup it should return only ID 1 because 1 appears twice in Table 1 :
ID
1
I have tried to do a JOIN on the tables and then apply a COUNT but nothing came out.
Thanks in advance!
Here is one method that I think will work in MS Access:
(select id
from table1
group by id
having count(*) > 1
) union -- note: NOT union all
(select id
from table2
group by id
having count(*) > 1
);
MS Access does not allow union/union all in the from clause. Nor does it support full outer join. Note that the union will remove duplicates.
Simple Group By and Having clause should help you
select ID
From Table1
Group by ID
having count(1)>1
union
select ID
From Table2
Group by ID
having count(1)>1
Based on your description, you do not need to join tables to find duplicate records, if your table is what you gave above, simply use:
With A
as
(
select ID,count(*) as Times From table group by ID
)
select * From A where A.Times>1
Not sure I understand what query you already tried, but this should work:
select table1.ID
from table1 inner join table2 on table1.id = table2.id
group by table1.ID
having count(*) > 1
Or if you have ID's in one table but not the other
select table1.ID
from table1 full outer join table2 on table1.id = table2.id
group by table1.ID
having count(*) > 1
I have 2 Tables, the table1 and table2.
Table1 has columns P_KEY, ID, some_value, some_value2, ....
Table2 has columns P2_KEY, RELATED_DATA, F_KEY, DATA_VALUE.
P_KEY and ID of table1 are unique pairs.
For each P_KEY (and thus each ID) of table1 there are multiple F_KEY entries of table2 with various data of each ID.
The RELATED_DATA rows have specific values (from a defined range elsewhere), which define the kind of Data stored for each ID.
I need to select the DATA_VALUE of ID where RELATED_DATA is 1 and 500. If one of them or both do not exist, I still want to display the row with (examples):
ID, DATA_VALUE (where RELATED_DATA=500), <empty column>
ID, <empty column>, DATA_VALUE (where RELATED_DATA=1)
ID, <empty column>, <empty column>
ID, DATA_VALUE (where RELATED_DATA=500), DATA_VALUE (where RELATED_DATA=1)
I have an SQL like the below, and I need to display row for A.ID, even when B1.RELATED_DATA and/or B2.RELATED_DATA do NOT exist (no row entry at table2), or this is empty string, having the B1.DATA_VALUE and/or B2.DATA_VALUE cell(s) showing as empty cell(s):
select A.ID, B1.DATA_VALUE, B2.DATA_VALUE
from table1 A, table2 B1, table2 B2
where B1.F_KEY = A.P_KEY
and B2.F_KEY = A.P_KEY
and B1.RELATED_DATA = 500
and B2.RELATED_DATA = 1
and A.ID='OneValue';
Purpose is to know the cases at which when B1.RELATED_DATA=500 and/or B2.RELATED_DATA=1 row do not exist or they are empty strings for ID.
Thank you.
What you'd need to do is to pivot the rows in table2 to get the two data_values as columns, rather than rows. Then you can join that back to table1 like so:
select a.id,
b.data_value_500,
b.data_value_1
from table1 a
inner join (select f_key,
max(case when related_data = 500 then data_value end) data_value_500,
max(case when related_data = 1 then data_value end) data_value_1
from table2
group by f_key) b on (a.p_key = b.f_key)
where a.id = 'OneValue';
N.B. I've used an inner join under the assumption that there will always be a row present in table2 for each p_key in table1. If that's not the case, switch to a left outer join instead.
Also, if you're on Oracle 11g or above, it's possible to use the built in PIVOT functionality to do the pivoting of table2:
select a.id,
b.data_value_500,
b.data_value_1
from table1 a
inner join (select f_key,
data_value_1,
data_value_500
from table2
pivot (max(data_value) for related_data in (1 as data_value_1,
500 as data_value_500)))
where a.id = 'OneValue';
I have the following tables in Oracle 10g:
Table1
Name Status
a closed
b live
c live
Table2
Name Status
a final
b live
c live
There are no primary keys in both tables, and I am trying to write a query which will return identical rows without looping both tables and comparing rows/columns. If the status column is different then the row in the Table2 takes presedence.
So in the above example my query should return this:
Name Status
a final
b live
c live
Since you have mentioned that there are no Primary Key on both tables, I'm assuming that there maybe a possibility that a row may exist on Table1, Table2, or both. The query below uses Common Table Expression and Windowing function to get such result.
WITH unionTable
AS
(
SELECT Name, Status, 1 AS ordr FROM Table1
UNION
SELECT Name, Status, 2 AS ordr FROM Table2
),
ranks
AS
(
SELECT Name, Status,
ROW_NUMBER() OVER (PARTITION BY NAME ORDER BY ordr DESC) rn
FROM unionTable
)
SELECT Name, Status
FROM ranks
WHERE rn = 1
SQLFiddle Demo
Something like this?
SELECT table1.Name, table2.Status
FROM table1
INNER JOIN table2 ON table1.Name = table2.Name
By always returning table2.Status you've covered both the case when they're the same and when they're different (essentially it doesn't matter what the value of table1.Status is).
I've got a query joining several tables and returning quite a few columns.
An indexed column of another table references the PK of one of these joined tables. Now I would like to add another column to the query that states if at least one row with that ID exists in the new table.
So if I have one of the old tables
ID
1
2
3
and the new table
REF_ID
1
1
1
3
then I'd like to get
ID REF_EXISTS
1 1
2 0
3 1
I can think of several ways to do that, but what is the most elegant/efficient one?
EDIT
I tested the performance of the queries provided with 50.000 records in the old table, every other record matched by two rows in the new table, so half of the records have REF_EXISTS=1.
I'm adding average results as comments to the answers in case anyone is interested. Thanks everyone!
Another option:
select O.ID
, case when N.ref_id is not null then 1 else 0 end as ref_exists
from old_table o
left outer join (select distinct ref_id from new_table) N
on O.id = N.ref_id
I would:
select distinct ID,
case when exists (select 1 from REF_TABLE where ID_TABLE.ID = REF_TABLE.REF_ID)
then 1 else 0 end
from ID_TABLE
Provided you have indexes on the PK and FK you will get away with a table scan and index lookups.
Regards
K
Use:
SELECT DISTINCT t1.id,
CASE WHEN t2.ref_id IS NULL THEN 0 ELSE 1 END AS REF_EXISTS
FROM TABLE_1 t1
LEFT JOIN TABLE_2 t2 ON t2.ref_id = t1.id
Added DISTINCT to ensure only unique rows are displayed.
A join could return multiple rows for one id, as it does for id=1 in the example data. You can limit it to one row per id with a group by:
SELECT
t1.id
, COUNT(DISTINCT t2.ref_id) as REF_EXISTS
FROM TABLE_1 t1
LEFT JOIN TABLE_2 t2 ON t2.ref_id = t1.id
GROUP BY t1.id
The group by ensures there's only one row per id. And count(distinct t2.ref_id) will be 1 if a row is found and 0 otherwise.
EDIT: You can rewrite it without a group by, but I doubt that will make things easer:
SELECT
t1.id
, CASE WHEN EXISTS (
SELECT * FROM TABLE_2 t2 WHERE t2.ref_id = t1.id)
THEN 1 ELSE 0 END as REF_EXISTS
, ....
FROM TABLE_1 t1